Would a bad PCV valve cause my check engine light to flash?
In my opinion, a bad PCV valve would cause your check engine light to flash because it comes on when a problem is detected by the self diagnosis system of your vehicle. Check with a mechanic immediately to rectify the problem for you.
If the check engine light has come on check the code stored in the computer. Autozone will do it for you. Many many things can cause a check engine light. Don't guess.
Don't think so, unless the hose or valve is leaking vacuum